1. Field of the Invention
The present invention relates to a cylindrical grinder, and more particularly to a cylindrical grinder which includes a workpiece support section for supporting and rotating a workpiece, and a wheel head for supporting and rotating a grinding wheel, and which grinds an outer surface of the workpiece through movement of the wheel head relative to the workpiece along a direction parallel to the axis of the workpiece and along a radial direction of the workpiece.
The present invention also relates to a mechanism for producing relative movement between a grinding wheel and a workpiece in a cylindrical grinder of the above-described type.
2. Description of the Related Art
As shown in FIG. 1, a cylindrical grinder 100 includes a workpiece support section 110 for supporting and rotating a workpiece W, and a wheel head 120 for supporting and rotating a grinding wheel T. In the cylindrical grinder 100, the wheel head 120 is moved relative to the workpiece W, which is supported on the workpiece support section 110, along a direction parallel to the rotational axis Ws of the workpiece (Z-axis direction) and along a radial direction of the workpiece (X-axis direction), in order to grind an outer surface of the workpiece W. Notably, in general, the wheel head 120 is disposed in such a manner that the rotational axis Ws of the workpiece W becomes parallel to the rotational axis Ts of the grinding wheel T.
In the cylindrical grinder 100, circumferential surfaces and end surfaces of the workpiece W are ground by means of circumferential and end surfaces of the grinding wheel T, which assumes a disc-like shape. In such a grinder, grinding burn is prone to occur when an end surface of the grinding wheel T comes into contact with an end surface of the workpiece W over a wide area. In order to obviate such a drawback, conventionally, grinding of end surfaces has been performed at lowered machining efficiency, or a so-called angular-slide grinding as shown in FIG. 2 has been employed. In the angular-slide grinding, the rotational axis Ts of the grinding wheel T is slightly tilted relative to the rotational axis Ws of the workpiece W within a plane passing through these axes Ts and Ws; and circumferential and end surfaces of the workpiece W are ground by means of a corner portion of the tilted grinding wheel T.
However, when angular-slide grinding is performed by use of the conventional cylindrical grinder 100, only one of the opposite end surfaces of the workpiece W (only the right-hand end surface in the example shown in FIG. 2) can be ground, and therefore, the workpiece W must be turned through 180° in a horizontal plane (hereinafter referred to as “inversion operation”) before grinding of the other end surface. Such turning of the workpiece W increases the number of steps required for grinding the opposite end surfaces of the workpiece W.
Another conceivable arrangement for a cylindrical grinder is such that one grinding wheel is provided on each of the opposite sides of a wheel head, which is rotatably supported in order to tilt the rotational axes of the grinding wheels relative to the rotational axis of a workpiece within a plane passing through these axes. This arrangement enables grinding of opposite end surfaces of the workpiece without involvement of the above-described inversion operation. However, in this case, since a grinding wheel is provided on each of the opposite sides of the wheel head, the size of the wheel head increases, and the grinding wheel that is not used for on-going grinding may interfere with the workpiece or the workpiece support section. Therefore, when a grinding wheel is provided on each of the opposite sides of the wheel head, limitations are imposed on shapes of workpieces which can be ground, thereby impairing the versatility of the cylindrical grinder.